// Edition2: 全局变量。

#include <stdio.h>

double fahr, cel;

void temchange();

int main()
{
    printf("Please input the Fahr:");
    scanf("%lf", &fahr);

    temchange(fahr, cel);

    printf("\nCel = %4.2lf\n", cel);

    return 0;
}

void temchange()
{
    printf("\nUsing temchange()...\n");
    cel = 5.0 * (fahr - 32) / 9.0;
}